Thermodynamic, economic and environmental assessment of energy systems including the use of gas from manure fermentation in the context of the Spanish potential

One of the prospective technologies that can be used for energy generation in distributed systems is based on biogas production, usually involving fermentation of various types of biomass and waste. This article aims to bring novelty on the analysis of this type of systems, joining together thermodynamic, economic and environmental aspects for a cross-cutting evaluation of the proposed solutions. The analysis is made for Spain, for which such a solution is very promising due to availability of the feedstock. A detailed simulation model of the proposed system in two different cases was built in Aspen Plus software and Visual Basic for Applications. Case 1 involves production of biogas in manure fermentation process, its upgrading (cleaning and removal of CO2 from the gas) and injection to the grid. Case 2 assumes combustion of the biogas in gas engine to produce electricity and heat that can be used locally and/or sold to the grid. Thermodynamic assessment of these two cases was made to determine the most important parameters and evaluation indices. The results served as input values for the economic analysis and environmental evaluation through Life Cycle Assessment of the energy systems. The results show that the analysed technologies have potential to produce high-value products based on low-quality biomass. Economic evaluation determined the break-even price of biomethane (Case 1) and electricity (Case 2), which for the nominal assumptions reach the values of 16.77 €/GJ and 28.92 €/GJ, respectively. In terms of environmental assessment the system with the use of biogas in gas engine presents around three times better environmental profile than Case 1 in the two categories evaluated, i.e., carbon and energy footprint.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 799439. Dr. Martín-Gamboa states that thanks are due to FCT/MCTES for the financial support to CESAM (UID/AMB/50017/2019), through national funds

Automatic Text Summarization Approaches to Speed up Topic Model Learning Process

The number of documents available into Internet moves each day up. For this reason, processing this amount of information effectively and expressibly becomes a major concern for companies and scientists. Methods that represent a textual document by a topic representation are widely used in Information Retrieval (IR) to process big data such as Wikipedia articles. One of the main difficulty in using topic model on huge data collection is related to the material resources (CPU time and memory) required for model estimate. To deal with this issue, we propose to build topic spaces from summarized documents. In this paper, we present a study of topic space representation in the context of big data. The topic space representation behavior is analyzed on different languages. Experiments show that topic spaces estimated from text summaries are as relevant as those estimated from the complete documents. The real advantage of such an approach is the processing time gain: we showed that the processing time can be drastically reduced using summarized documents (more than 60\% in general). This study finally points out the differences between thematic representations of documents depending on the targeted languages such as English or latin languages.Comment: 16 pages, 4 tables, 8 figure

Síntesis de Hexaferrita de Bario a partir de lejias ferrosas residuales de decapado

Las lejías de decapado son el principal foco de contaminación hídrica en la industria siderúrgica. En la bibliografía se encuentran distintos procesos para su tratamiento, pero presentan diversos inconvenientes técnicos o económicos que los inhabilitan en la actualidad. En esta tesis doctoral se propone la oxiprecipitación como el procedimiento optimo para el aprovechamiento de las lejías del decapado con ácido sulfúrico. En este sentido se ha estudiado la influencia de las variables que afectan a este proceso, se ha optimado los intervalos experimentales de síntesis, se determinan el mecanismo y el modelo cinético de la reacción y se presentan dos modelos matemáticos de la obtención de goetita y magnetita, productos de la oxiprecipitación de disoluciones ferrosas sulfúricas. Con el fin de estudiar la aplicación de los oxiprecipitados de hierro, se realiza la síntesis de hexaferrita de bario por método cerámico con estos productos comparándolos con óxidos de hierro comerciales, llegando a sintetizar ferritas con propiedades magnéticas superiores a los estándares

Revisiting the role of steam methane reforming with CO2 capture and storage for long-term hydrogen production

Road transport is associated with high greenhouse gas emissions due to its current dependence on fossil fuels. In this regard, the implementation of alternative fuels such as hydrogen is expected to play a key role in decarbonising the transport system. Nevertheless, attention should be paid to the suitability of hydrogen production pathways as low-carbon solutions. In this work, an energy systems optimisation model for the prospective assessment of a national hydrogen production mix was upgraded in order to unveil the potential role of grey hydrogen from steam methane reforming (SMR) and blue hydrogen from SMR with CO2 capture and storage (CCS) in satisfying the hydrogen demanded by fuel cell electric vehicles in Spain from 2020 to 2050. This was done by including CCS retrofit of SMR plants in the energy systems model, as a potential strategy within the scope of the European Hydrogen Strategy. Considering three hypothetical years for banning hydrogen from fossil-based plants without CCS (2030, 2035, and 2040), it was found that SMR could satisfy the whole demand for hydrogen for road transport in the short term (2020–2030), while being substituted by water electrolysis in the medium-to-long term (2030–2050). Furthermore, this trend was found to be associated with an appropriate prospective behaviour in terms of carbon footprint.This research has been partly supported by the Spanish Ministry of Economy, Industry and Competitiveness (ENE2015-74607-JIN AEI/FEDER/UE)

A kinetic reaction model for biomass pyrolysis processes in Aspen Plus

This paper presents a novel kinetic reaction model for biomass pyrolysis processes. The model is based on the three main building blocks of lignocellulosic biomass, cellulose, hemicellulose and lignin and can be readily implemented in Aspen Plus and easily adapted to other process simulation software packages. It uses a set of 149 individual reactions that represent the volatilization, decomposition and recomposition processes of biomass pyrolysis. A linear regression algorithm accounts for the secondary pyrolysis reactions, thus allowing the calculation of slow and intermediate pyrolysis reactions. The bio-oil is modelled with a high level of detail, using up to 33 model compounds, which allows for a comprehensive estimation of the properties of the bio-oil and the prediction of further upgrading reactions. After showing good agreement with existing literature data, our own pyrolysis experiments are reported for validating the reaction model. A beech wood feedstock is subjected to pyrolysis under well-defined conditions at different temperatures and the product yields and compositions are determined. Reproducing the experimental pyrolysis runs with the simulation model, a high coincidence is found for the obtained fraction yields (bio-oil, char and gas), for the water content and for the elemental composition of the pyrolysis products. The kinetic reaction model is found to be suited for predicting pyrolysis yields and product composition for any lignocellulosic biomass feedstock under typical pyrolysis conditions without the need for experimental data

NCDiacetyl

We worked with North Country Cider in NH to improve the taste of the hard cider. The goal was to investigate the cause and potential solution to the increased levels of diacetyl found in their ciders made with Ginger Gold and Jonah Gold apples. We utilized the brewing supplies in the Unit Operations Lab in Goddard Hall at WPI to replicate the process and tested our samples using a refractometer and an IR Spectroscopy machine in the Biomedical Engineering department. The team found that there was no strong correlation between different brewing parameters and the levels of diacetyl found, leading us to believe that the diacetyl must be found in the batches of apples utilized for the process. Further investigation into the apples would be beneficial in order to confirm this conclusion

Exergetic analysis of hybrid power plants with biomass and photovoltaics coupled with a solid-oxide electrolysis system

This paper studies four hybrid systems that couple a reference biomass and photovoltaic power plant with four different structures of a steam electrolysis system for hydrogen production. The four hybrid plants are initially examined incorporating the same capacity components as the reference plant. The integration of different structures of the electrolysis process results in operational penalties when compared to the reference plant, due to added irreversibilities intrinsic to the electrolysis process and the reduction of the biomass plant efficiency from the extraction of low-pressure steam used to evaporate the electrolyzer feed water. The magnitude of these penalties depends on the power consumption of the electrolysis system, thermal demand and/or pressure losses within incorporated plant components. Among the alternative scenarios, the maximum efficiency is achieved when the electrolysis system works with a recycling sweep gas stream further used in the boiler of the biomass power plant. Furthermore, the efficiencies of the electrolysis hybrid plants only surpass that of the reference power plant when the solar irradiation drops to 36-46%. This is a direct result of the lower operational efficiency of the solar panels versus the biomass plant. (C) 2015 Elsevier Ltd. All rights reserved.The authors would like to acknowledge the project ADEL co-funded by of the 7th Framework Programme of the European Union (FP7) and the Fuel Cells and Hydrogen Joint Undertaking (FCH-JU). Fontina Petrakopoulou would like to thank the IEF Marie Curie Action PEOPLE-2012-IEFGENERGIS- 332028 funded by FP7

Life cycle assessment of a novel strategy based on hydrothermal carbonization for nutrient and energy recovery from food waste

In this work, a novel strategy for food waste valorization was evaluated from an environmental life-cycle perspective. A system based on acid-assisted hydrothermal carbonization of food waste combined with the exploitation of hydrochar by combustion and process water through nutrient recovery stage and subsequent anaerobic digestion, was assessed and compared with stand-alone anaerobic digestion as the reference system. This combination of processes aims to recover both nutrients in a stage of struvite precipitation from process water and energy through hydrochar and biogas combustion. Both systems were modeled in Aspen Plus® to identify and quantify their most relevant input and output flows and subsequently evaluate their environmental performance through the life cycle assessment methodology. The novel combined system was found to generally involve a more favorable environmental performance than the reference stand-alone configuration, which would be closely linked to the substitution of hydrochar for fossil fuels. In addition, the impacts associated with soil application of the struvite produced in the integrated process would also be reduced compared to the use of the digestate generated in the stand-alone anaerobic digestion process. Following these results and the evolving regulatory framework for biomass waste management, mainly in the field of nutrient recovery, combined process based on acid-assisted hydrothermal treatment plus nutrient recovery stage and anaerobic digestion is concluded to be a promising circular economy concept for food waste valorizationThe authors greatly appreciate funding from Spanish MICINN (Project PID2019-108445RB-I00; PDC2021-120755-I00) and the Madrid Regional Government (Project S2018/EMT-4344). A. Sarrion wishes to thank the Spanish MICINN and ESF for a research grant (BES-2017-081515

Detection and Preliminary Characterisation of Polluted White Dwarfs from Gaia EDR3 and LAMOST

We present a catalogue of 62 polluted white dwarfs observed by the 9th Low-Resolution Data Release of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST LRS DR9v1; R$\approx$1,800) and the Early Data Release 3 (EDR3) of the Gaia Mission. Among these stellar remnants, 30 are new discoveries with previously unknown traces of calcium pollution. To generate our catalogue, we used a database of 4,324 unique Gaia EDR3 white dwarf candidates with LAMOST LRS DR9v1 observations, many of which have been spectroscopically confirmed by other telescopes. For these stars, we developed a quantitative method to detect calcium absorption in their spectra between 3,900-4,000$\mathring {\mathrm A}$, which we then validated through visual inspection and multiple literature cross-checks. Our catalogue provides the astrometric and photometric properties of the white dwarf candidates, incorporates supplementary data (e.g. Montreal White Dwarf Database, MWDD; PanSTARRS; the Hubble Space Telescope), and indicates the possibility of calcium pollution in their atmospheres. For our final sample of polluted white dwarfs, we also determine the main atmospheric properties of 23 sources with effective temperatures $T_{\rm eff}$$\leq$25,000K and no existing calcium abundances in the MWDD. Our analysis represents a first step towards measuring the full atmospheric composition of these stars and learning about the bulk properties of their accreted material. As we venture into the era of wide-field spectroscopic surveys, our work highlights the importance of combining large-scale databases for identifying and characterising new polluted white dwarfs.Comment: 29 pages, 14 figures (+3 in the Appendix), 5 tables (+5 in the Appendix). Accepted for publication in MNRA